Subdomains in DNS - What are...

Subdomains are prefixes to domain names that allow administrators to provide different web services to users, but do so using the same namespace so that it is easier to remember. Such as MAIL.failednormal.com, WWW.failednormal.com, VPN.failednormal.com... these subdomains can point to entirely different servers so that WWW points to the IP Adress of your web server, MAIL points to your companies Gmail landing page, and VPN points to your VPN provider.